1. Field of the Invention
This invention relates to an archery bow limb construction wherein a bow limb is mounted to a bow handle or riser.
2. Description of the Related Art
Referring to FIG. 1 of the attached drawings, a cross sectional view of a typical prior art bow limb construction 10 is shown. A bow limb 12 threadably engages a bow handle or riser 14 through a mounting screw 16 and a pair of ball mounts 18 (only one ball mount 18 is shown). The ball mounts 18 have a mushroom shape and comprise a cylindrical portion 20, an integral hemispherical portion 22, and an annular flange 23 which is integral with the outer periphery of the cylindrical portion 20. The cylindrical portion of each ball mount fits into a countersunk bore 24 in a bottom surface 25 in the bow limb, and the hemispherical portion of each ball mount snugly fits into a hemispherical recess 26 in the riser. The annular flange 23 engages the bottom surface 25 of the bow limb. A proximate and 28 of the bow limb pivots longitudinally with respect to the riser about the ball mounts. The bow limb can longitudinally pivot, for example, to and between a first position A shown in phantom lines and a second position B shown in solid lines by threading the mounting screw into the riser or unthreading the mounting screw out of the riser, respectively.
The mounting screw extends through an aperture 30 in the bow limb and is threadably received in a countersunk threaded bore 32 of the riser and adjustably secures the bow limb to the riser. A washer 34 includes a bore for receiving and supporting the mounting screw and can be disposed between the head of the mounting screw and the bow limb. The bore of the washer 34 has an inwardly tapering annular surface which leads to a generally cylindrical hole. The inwardly tapering annular surface of the washer 34 serves as a seat for an annular chamfer 36 of the mounting screw. A flat washer 35 can be disposed between the washer 34 and the bow limb. With this construction, the mounting screw is rotatably received by the washer 34.
The mounting screw can be threaded into the riser to draw the proximate end of the bow limb closer to the riser (position A), or the mounting screw can be unthreaded to move the proximate end of the bow limb farther from the riser (position B). During this adjustment of the mounting screw, the bow limb pivots about the ball mounts. This adjustment of each bow limb relative to the riser provides a range of angular relationships between each bow limb and the riser with corresponding differences in the amount of force imparted to the arrow for a given pull distance on the draw string, thereby adjusting the maximum draw force of the bow.
There are two problems which are experienced with this mounting, however. The first problem is that the limb tends to twist sideways or laterally with respect to the riser, thereby resulting in a misalignment of the bow during draw. The second problem is that the mounting screw tends to back out of the countersunk threaded bore of the riser, especially in high performance bows. Thus, the mounting screw must be continually adjusted.
There is a need for an archery bow limb construction wherein the maximum draw force of the bow can be adjusted. The tendency of the bow limb to twist laterally relative to the riser must be minimized. Also, it would be most preferably if the bow limbs did not require continual adjustment relative to the riser.